// Copyright (c) 2011 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "base/synchronization/condition_variable.h"

#include <errno.h>
#include <stdint.h>
#include <sys/time.h>

#include "base/synchronization/lock.h"
#include "base/threading/thread_restrictions.h"
#include "base/time/time.h"
#include "build/build_config.h"

namespace base {

ConditionVariable::ConditionVariable(Lock* user_lock)
    : user_mutex_(user_lock->lock_.native_handle())
#if DCHECK_IS_ON()
    , user_lock_(user_lock)
#endif
{
    int rv = 0;
    // http://crbug.com/293736
    // NaCl doesn't support monotonic clock based absolute deadlines.
    // On older Android platform versions, it's supported through the
    // non-standard pthread_cond_timedwait_monotonic_np. Newer platform
    // versions have pthread_condattr_setclock.
    // Mac can use relative time deadlines.
#if !defined(OS_MACOSX) && !defined(OS_NACL) && !(defined(OS_ANDROID) && defined(HAVE_PTHREAD_COND_TIMEDWAIT_MONOTONIC))
    pthread_condattr_t attrs;
    rv = pthread_condattr_init(&attrs);
    DCHECK_EQ(0, rv);
    pthread_condattr_setclock(&attrs, CLOCK_MONOTONIC);
    rv = pthread_cond_init(&condition_, &attrs);
    pthread_condattr_destroy(&attrs);
#else
    rv = pthread_cond_init(&condition_, NULL);
#endif
    DCHECK_EQ(0, rv);
}

ConditionVariable::~ConditionVariable()
{
#if defined(OS_MACOSX)
    // This hack is necessary to avoid a fatal pthreads subsystem bug in the
    // Darwin kernel. http://crbug.com/517681.
    {
        base::Lock lock;
        base::AutoLock l(lock);
        struct timespec ts;
        ts.tv_sec = 0;
        ts.tv_nsec = 1;
        pthread_cond_timedwait_relative_np(&condition_, lock.lock_.native_handle(),
            &ts);
    }
#endif

    int rv = pthread_cond_destroy(&condition_);
    DCHECK_EQ(0, rv);
}

void ConditionVariable::Wait()
{
    base::ThreadRestrictions::AssertWaitAllowed();
#if DCHECK_IS_ON()
    user_lock_->CheckHeldAndUnmark();
#endif
    int rv = pthread_cond_wait(&condition_, user_mutex_);
    DCHECK_EQ(0, rv);
#if DCHECK_IS_ON()
    user_lock_->CheckUnheldAndMark();
#endif
}

void ConditionVariable::TimedWait(const TimeDelta& max_time)
{
    base::ThreadRestrictions::AssertWaitAllowed();
    int64_t usecs = max_time.InMicroseconds();
    struct timespec relative_time;
    relative_time.tv_sec = usecs / Time::kMicrosecondsPerSecond;
    relative_time.tv_nsec = (usecs % Time::kMicrosecondsPerSecond) * Time::kNanosecondsPerMicrosecond;

#if DCHECK_IS_ON()
    user_lock_->CheckHeldAndUnmark();
#endif

#if defined(OS_MACOSX)
    int rv = pthread_cond_timedwait_relative_np(
        &condition_, user_mutex_, &relative_time);
#else
    // The timeout argument to pthread_cond_timedwait is in absolute time.
    struct timespec absolute_time;
#if defined(OS_NACL)
    // See comment in constructor for why this is different in NaCl.
    struct timeval now;
    gettimeofday(&now, NULL);
    absolute_time.tv_sec = now.tv_sec;
    absolute_time.tv_nsec = now.tv_usec * Time::kNanosecondsPerMicrosecond;
#else
    struct timespec now;
    clock_gettime(CLOCK_MONOTONIC, &now);
    absolute_time.tv_sec = now.tv_sec;
    absolute_time.tv_nsec = now.tv_nsec;
#endif

    absolute_time.tv_sec += relative_time.tv_sec;
    absolute_time.tv_nsec += relative_time.tv_nsec;
    absolute_time.tv_sec += absolute_time.tv_nsec / Time::kNanosecondsPerSecond;
    absolute_time.tv_nsec %= Time::kNanosecondsPerSecond;
    DCHECK_GE(absolute_time.tv_sec, now.tv_sec); // Overflow paranoia

#if defined(OS_ANDROID) && defined(HAVE_PTHREAD_COND_TIMEDWAIT_MONOTONIC)
    int rv = pthread_cond_timedwait_monotonic_np(
        &condition_, user_mutex_, &absolute_time);
#else
    int rv = pthread_cond_timedwait(&condition_, user_mutex_, &absolute_time);
#endif // OS_ANDROID && HAVE_PTHREAD_COND_TIMEDWAIT_MONOTONIC
#endif // OS_MACOSX

    DCHECK(rv == 0 || rv == ETIMEDOUT);
#if DCHECK_IS_ON()
    user_lock_->CheckUnheldAndMark();
#endif
}

void ConditionVariable::Broadcast()
{
    int rv = pthread_cond_broadcast(&condition_);
    DCHECK_EQ(0, rv);
}

void ConditionVariable::Signal()
{
    int rv = pthread_cond_signal(&condition_);
    DCHECK_EQ(0, rv);
}

} // namespace base
